| /* |
| * Copyright (c) 2005, 2006, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package sun.misc; |
| |
| import java.io.BufferedReader; |
| import java.io.FileReader; |
| import java.io.File; |
| import java.io.IOException; |
| import java.util.ArrayList; |
| import java.util.Collections; |
| import java.util.HashMap; |
| import java.util.List; |
| import java.util.Map; |
| |
| /* |
| * MetaIndex is intended to decrease startup time (in particular cold |
| * start, when files are not yet in the disk cache) by providing a |
| * quick reject mechanism for probes into jar files. The on-disk |
| * representation of the meta-index is a flat text file with per-jar |
| * entries indicating (generally speaking) prefixes of package names |
| * contained in the jar. As an example, here is an edited excerpt of |
| * the meta-index generated for jre/lib in the current build: |
| * |
| <PRE> |
| % VERSION 1 |
| # charsets.jar |
| sun/ |
| # jce.jar |
| javax/ |
| ! jsse.jar |
| sun/ |
| com/sun/net/ |
| javax/ |
| com/sun/security/ |
| @ resources.jar |
| com/sun/xml/ |
| com/sun/rowset/ |
| com/sun/org/ |
| sun/ |
| com/sun/imageio/ |
| javax/ |
| com/sun/java/swing/ |
| META-INF/services/ |
| com/sun/java/util/jar/pack/ |
| com/sun/corba/ |
| com/sun/jndi/ |
| ! rt.jar |
| org/w3c/ |
| com/sun/imageio/ |
| javax/ |
| sunw/util/ |
| java/ |
| sun/ |
| ... |
| </PRE> |
| * <p> A few notes about the design of the meta-index: |
| * |
| * <UL> |
| * |
| * <LI> It contains entries for multiple jar files. This is |
| * intentional, to reduce the number of disk accesses that need to be |
| * performed during startup. |
| * |
| * <LI> It is only intended to act as a fast reject mechanism to |
| * prevent application and other classes from forcing all jar files on |
| * the boot and extension class paths to be opened. It is not intended |
| * as a precise index of the contents of the jar. |
| * |
| * <LI> It should be as small as possible to reduce the amount of time |
| * required to parse it during startup. For example, adding on the |
| * secondary package element to java/ and javax/ packages |
| * ("javax/swing/", for example) causes the meta-index to grow |
| * significantly. This is why substrings of the packages have been |
| * chosen as the principal contents. |
| * |
| * <LI> It is versioned, and optional, to prevent strong dependencies |
| * between the JVM and JDK. It is also potentially applicable to more |
| * than just the boot and extension class paths. |
| * |
| * <LI> Precisely speaking, it plays different role in JVM and J2SE |
| * side. On the JVM side, meta-index file is used to speed up locating the |
| * class files only while on the J2SE side, meta-index file is used to speed |
| * up the resources file & class file. |
| * To help the JVM and J2SE code to better utilize the information in meta-index |
| * file, we mark the jar file differently. Here is the current rule we use. |
| * For jar file containing only class file, we put '!' before the jar file name; |
| * for jar file containing only resources file, we put '@' before the jar file name; |
| * for jar file containing both resources and class file, we put '#' before the |
| * jar name. |
| * Notice the fact that every jar file contains at least the manifest file, so when |
| * we say "jar file containing only class file", we don't include that file. |
| * |
| * </UL> |
| * |
| * <p> To avoid changing the behavior of the current application |
| * loader and other loaders, the current MetaIndex implementation in |
| * the JDK requires that the directory containing the meta-index be |
| * registered with the MetaIndex class before construction of the |
| * associated URLClassPath. This prevents the need for automatic |
| * searching for the meta-index in the URLClassPath code and potential |
| * changes in behavior for non-core ClassLoaders. |
| * |
| * This class depends on make/tools/MetaIndex/BuildMetaIndex.java and |
| * is used principally by sun.misc.URLClassPath. |
| */ |
| |
| public class MetaIndex { |
| // Maps jar file names in registered directories to meta-indices |
| private static volatile Map<File, MetaIndex> jarMap; |
| |
| // List of contents of this meta-index |
| private String[] contents; |
| |
| // Indicate whether the coresponding jar file is a pure class jar file or not |
| private boolean isClassOnlyJar; |
| |
| //---------------------------------------------------------------------- |
| // Registration of directories (which can cause parsing of the |
| // meta-index file if it is present), and fetching of parsed |
| // meta-indices |
| // jarMap is not strictly thread-safe when the meta index mechanism |
| // is extended for user-provided jar files in future. |
| |
| public static MetaIndex forJar(File jar) { |
| return getJarMap().get(jar); |
| } |
| |
| // 'synchronized' is added to protect the jarMap from being modified |
| // by multiple threads. |
| public static synchronized void registerDirectory(File dir) { |
| // Note that this does not currently check to see whether the |
| // directory has previously been registered, since the meta-index |
| // in a particular directory creates multiple entries in the |
| // jarMap. If this mechanism is extended beyond the boot and |
| // extension class paths (for example, automatically searching for |
| // meta-index files in directories containing jars which have been |
| // explicitly opened) then this code should be generalized. |
| // |
| // This method must be called from a privileged context. |
| File indexFile = new File(dir, "meta-index"); |
| if (indexFile.exists()) { |
| try { |
| BufferedReader reader = new BufferedReader(new FileReader(indexFile)); |
| String line = null; |
| String curJarName = null; |
| boolean isCurJarContainClassOnly = false; |
| List<String> contents = new ArrayList<String>(); |
| Map<File, MetaIndex> map = getJarMap(); |
| |
| /* Convert dir into canonical form. */ |
| dir = dir.getCanonicalFile(); |
| /* Note: The first line should contain the version of |
| * the meta-index file. We have to match the right version |
| * before trying to parse this file. */ |
| line = reader.readLine(); |
| if (line == null || |
| !line.equals("% VERSION 2")) { |
| reader.close(); |
| return; |
| } |
| while ((line = reader.readLine()) != null) { |
| switch (line.charAt(0)) { |
| case '!': |
| case '#': |
| case '@': { |
| // Store away current contents, if any |
| if ((curJarName != null) && (contents.size() > 0)) { |
| map.put(new File(dir, curJarName), |
| new MetaIndex(contents, |
| isCurJarContainClassOnly)); |
| |
| contents.clear(); |
| } |
| // Fetch new current jar file name |
| curJarName = line.substring(2); |
| if (line.charAt(0) == '!') { |
| isCurJarContainClassOnly = true; |
| } else if (isCurJarContainClassOnly) { |
| isCurJarContainClassOnly = false; |
| } |
| |
| break; |
| } |
| case '%': |
| break; |
| default: { |
| contents.add(line); |
| } |
| } |
| } |
| // Store away current contents, if any |
| if ((curJarName != null) && (contents.size() > 0)) { |
| map.put(new File(dir, curJarName), |
| new MetaIndex(contents, isCurJarContainClassOnly)); |
| } |
| |
| reader.close(); |
| |
| } catch (IOException e) { |
| // Silently fail for now (similar behavior to elsewhere in |
| // extension and core loaders) |
| } |
| } |
| } |
| |
| //---------------------------------------------------------------------- |
| // Public APIs |
| // |
| |
| public boolean mayContain(String entry) { |
| // Ask non-class file from class only jar returns false |
| // This check is important to avoid some class only jar |
| // files such as rt.jar are opened for resource request. |
| if (isClassOnlyJar && !entry.endsWith(".class")){ |
| return false; |
| } |
| |
| String[] conts = contents; |
| for (int i = 0; i < conts.length; i++) { |
| if (entry.startsWith(conts[i])) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| |
| //---------------------------------------------------------------------- |
| // Implementation only below this point |
| // @IllegalArgumentException if entries is null. |
| private MetaIndex(List<String> entries, boolean isClassOnlyJar) |
| throws IllegalArgumentException { |
| if (entries == null) { |
| throw new IllegalArgumentException(); |
| } |
| |
| contents = entries.toArray(new String[0]); |
| this.isClassOnlyJar = isClassOnlyJar; |
| } |
| |
| private static Map<File, MetaIndex> getJarMap() { |
| if (jarMap == null) { |
| synchronized (MetaIndex.class) { |
| if (jarMap == null) { |
| jarMap = new HashMap<File, MetaIndex>(); |
| } |
| } |
| } |
| assert jarMap != null; |
| return jarMap; |
| } |
| } |
